Improvements in Wintertime Surface Temperature Variability in the Community Earth System Model Version 2 (CESM2) Related to the Representation of Snow Density
Improvements in Wintertime Surface Temperature Variability in the Community Earth System Model Version 2 (CESM2) Related to the Representation of Snow Density
复制标题
社区地球系统模型版本 2 (CESM2) 中与雪密度表示相关的冬季地表温度变化的改进
DOI：
10.1029/2021ms002880
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发表时间：
2022
影响因子：
6.8
通讯作者：
Truesdale, John E.
中科院分区：
文献类型：
--
作者：
Simpson, Isla R.;Lawrence, David M.;Swenson, Sean C.;Hannay, Cecile;McKinnon, Karen A.;Truesdale, John E.
共同体地球系统模型(CESM)被广泛用于预测和理解气候变异性和变化。对近地表气温(T2M)行为的准确模拟在这样的模型中对于解决与社会相关的问题至关重要。然而，以前版本的CESM高估了北半球陆地地区冬季T2m的可变性。结果表明，最新版本的CESM(CESM2)比以前的版本对冬季T2m变率的描述有了很大的改善，现在它与观测结果吻合得很好。一系列有针对性的实验表明，这一改善的一个重要因素是陆地表面组成部分内雪密度的变化对当地的影响。CESM2中雪密度的增加导致了雪层电导率的增加。因此，在T2异常的存在下，通过雪层的热通量更大，从而导致地面和近地面大气温度异常的更大的抑制。通过对CESM1和CESM2大型集合的比较，也考虑了CESM2对未来预测的影响。与CESM1相比，与CESM1相比，CESM2在未来NH冬季平均温度的预测中表现出较小的集合扩散，在气候变化下每日冬季T2m变率的下降幅度较小。总体而言，这一改进提高了CESM2作为研究冬季T2m变异性和变化的工具的准确性。
The Community Earth System Model (CESM) is widely used for the prediction and understanding of climate variability and change. Accurate simulation of the behavior of near surface air temperature (T2m) is critical in such a model for addressing societally relevant problems. However, previous versions of CESM suffered from an overestimation of wintertimeT2mvariability in Northern Hemisphere (NH) land regions. Here, it is shown that the latest version of CESM (CESM2) exhibits a much improved representation of wintertimeT2mvariability compared to its predecessor and it now compares well with observations. A series of targeted experiments reveal that an important contributor to this improvement is the local effects of changes to the representation of snow density within the land surface component. Increased snow densities in CESM2 lead to enhanced conductance of the snow layer. As a result, larger heat fluxes across the snow layer are induced in the presence ofT2manomalies, leading to a greater dampening of surface and near surface atmospheric temperature anomalies. The implications for future projections with CESM2 are also considered through comparison of the CESM1 and CESM2 large ensembles. Aligned with the reduction in surface temperature variability, compared to CESM1, CESM2 exhibits reduced ensemble spread in future projections of NH winter mean temperature and a smaller decline in daily wintertimeT2mvariability under climate change. Overall, this improvement has increased the accuracy of CESM2 as a tool for the study of wintertimeT2mvariability and change.
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影响因子：
9.8
作者：
Pastorello, Gilberto;Trotta, Carlo;Papale, Dario
通讯作者：
Papale, Dario
影响因子：
4.6
作者：
Deser, Clara;Phillips, Adam;Teng, Haiyan
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Teng, Haiyan
影响因子：
30.7
作者：
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通讯作者：
Screen, James A.
影响因子：
5.2
作者：
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通讯作者：
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